ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
591 
over the blotting paper, and thus the sections are firmly fixed to the 
slide. The sections are then brushed over with a soft large camel’s 
hair brush, and returned to the shelf of the water-bath, on which are 
placed several layers of black cardboard. The sections dry in from 
ten minutes to an hour, and may then be manipulated with impunity, or 
stored away for future use. 
Brasilin , says the author, is a very good stain, in many respects 
being superior to haematoxylin. It should be mixed in the same way as 
Bohmer’s haematoxylin. After a few weeks the stain ripens into a deep 
red, with copious precipitate of blue flakes insoluble in water. The 
flakes are collected in a filter, and dissolved in 95 per cent, alcohol, 
and 15 per cent, of glycerin added. This solution is superior to the 
original solution, and stains nuclei a deep red. 
Iron lisematoxylin. The sections are immersed for 12 hours or more 
in liq. ferri sulf. oxidati diluted at least five times. Before being placed 
in the haematoxylin bath the sections should be washed for at least one 
minute in water. The saturated aqueous solution, which should contain 
10 per cent, of alchol, is diluted for use with from ten to twenty times 
the amount of distilled water, and the sections immersed therein for 
12 hours or more. Differentiation is then made with the same liq. ferri 
greatly diluted, or with 25 per cent, (or less) formic, acetic, or other 
acid, or with mixtures of acids and liq. ferri. In using this method it 
is important to remove all traces of alcohol from the sections before 
they are placed in the liq. ferri. 
Tliionin-ruthenium-red. This combination will produce opposite re- 
sults according to the length of time occupied by the thionin-staining, 
or the age of the ruthenium mixture. 
(1) Stain first for 5 minutes with aqueous 1 per cent, solution of 
thionin with 10 per cent, of alcohol. Binse in distilled water, and then 
put on the section a few drops of ruthenium-red (made by dissolving in 
80 per cent, distilled and filtered water, 10 per cent, absolute alcohol, and 
10 per cent, glycerin). When the cells in mitosis exhibit a red cyto- 
plasm and dark blue chromosomes, as observed under the Microscope, 
the differentiation is checked. Dehydrate with absolute alcohol, clear 
with pure fresh bergamot oil, and follow at once with xylol. 
(2) Stain for 12-24 hours in a very weak solution of thionin (a 
couple of drops of 1 per cent, solution in a Naples jar of water). Binse 
in distilled water, and differentiate as before with ruthenium-red. De- 
hydrate and clear as before. By the first procedure the chromosomes 
are stained blue, by the latter red, or reddish-brown, and so on. 
Gum-thus. This substance is a gum from a Binus indigenous to the 
Eastern United States ; it is dissolved in xylol ; it dries quicker, and gives 
clearer and better definition, than Canada balsam. It has the additional 
merit of being much cheaper than balsam. 
Combined Method of Fixing and Staining Microscopic Prepara- 
tions.* — Herr M. B. Wermel has combined the fixation and staining of 
blood and muscle by the use of the following solution : — 1 methylen- 
formalin (saturated alkaline methylen-blue, 30 ccm. ; 2*5 per cent, aque- 
* Mcdizinskoje Obosrenje, May 1897. See Centralbl. Bakt. u. Par., 1‘® Abt., xxii. 
(1897) p. 419. 
